The US have imposed restrictions on all airports with direct flights to the US.Politikaner

The US Transportation Security Administration will not allow uncharged mobile phones or other electronic devices on US-bound planes at some overseas airports, it has been announced.

The new measure is part of the TSA's effort to strengthen airport security following intelligence to suggest that Islamic extremists are plotting to blow up an airliner.

Passengers at certain international airports may be asked during security screening, to turn on their electronic devices, such as mobile phones, tablet or laptop computers. If they do not have power, the devices will not be allowed on planes.

In a written statement. The TSA said: "As the travelling public knows all electronic devices are screened by security officers.

"During the security examination, officers may also ask that owners power up some devices, including cell phones.

"Powerless devices will not be permitted onboard the aircraft. The traveller may also undergo additional screening."

US officials fear bomb-makers from the Yemen-based al Qaeda in the Arabian Peninsula (AQAP) have devised a way of converting mobile phones, tablets, laptops and other electronic device into explosives which can avoid detection.

AQAP has a track record of plotting such attacks. The group's bomb maker, Ibrahim al-Asiri, built an underwear bomb used in a failed 2009 effort to bring down a Detroit-bound airliner. His devices were also in other plots.

American authorities have singled out Apple iPhones and Samsung Galaxy handsets for extra security checks following concerns regarding the new 'phone bombs.'

US authorities are also concerned that hard-to-detect bombs could be built into shoes.

There was no immediate indication U.S. intelligence had detected a specific plot or timeframe for any attack.

The TSA has not specified which airports will be subject to the extra screening, but the security measure would apply to US-bound direct flights from Europe, the Middle East and Africa.